A new study from the Energy Institute at the University of Texas at Austin has found "no evidence" of hydraulic fracturing or fracking leading to groundwater contamination.

Lead author Charles Groat said: "We found no direct evidence of the hydraulic fracturing itself -- the practice of fracturing the rocks -- had contaminated the shallow aquifer."

He added in a statement: "What we've tried to do is separate fact from fiction."

The results were circulated by Energy in Depth, a national pro-drilling industry group.

Tow Stewart, executive vice president of the Ohio Oil and Gas Association and executive director of Energy in Depth-Ohio, said the report validates what regulators and other scientists have long maintained.

"The University of Texas study confirms what previous studies have stated in its conclusion that hydraulic fracturing has not directly been tied to one instance of groundwater contaminat," he said in a statement.

The report says that many problems ascribed to hydraulic fracturing are related to processes common to oil-and-gas drilling operations, such as casing failures and poor cement jobs.